As an electro-photographic type image forming apparatus, there is known a printer including a housing and a photosensitive unit supporting a photosensitive drum that is detachably attached to the housing.
Japanese Patent Application Publication No. 2011-13268 discloses a printer, in which a photosensitive unit that has been detached from a frame member of the housing and positioned at a detached position is attached to the frame member as a result of insertion of the photosensitive unit in a diagonally downward direction after the photosensitive unit is inserted into the frame member in a horizontal direction.